1. Field of the Invention
The present invention relates to a binder for monolithic refractories, which is used for the lining or repair of kilns, and a monolithic refractory using the binder for monolithic refractories.
Priority is claimed on Japanese Patent Application No. 2008-274889, filed Oct. 24, 2008, the content of which is incorporated herein by reference.
2. Description of Related Art
As a binder for the lining refractories of kilns used for a variety of high temperature processes, best exemplified by steel processes, a number of organic and inorganic compounds, such as sodium phosphate, sodium silicate, a furan resin, a phenol resin, pitch, aluminum lactate, sodium aluminate, silica sol, alumina sol, polyvinyl alcohol, methylcellulose, carboxymethylcellulose, ethylsilicate, alumina cement, hydraulic alumina, or the like, are used.
In recent years, refractories have become unshaped for improvement in constructability, ease of repair, or the like, and monolithic refractories have become widely used even in parts that come into contact with molten iron or high temperature slag, for which shaped bricks were used in the past.
The manufacture of monolithic refractories does not include a high pressure press, which is performed in the manufacture of shaped refractories. Therefore, the characteristics of raw materials or binders are important. Among them, alumina cement (major chemical compounds: CaO.Al2O3, CaO.2Al2O3, 12CaO.7Al2O3) is used for a wide range of uses as a binder for refractories of a gutter, a ladle, a tundish, or the like.
Furthermore, investigation are also ongoing with alumina-based binders including chemical components other than CaO—Al2O3.
For example, Japanese Unexamined Patent Application, First Publication No. S52-148524 discloses mixtures of raw materials for the manufacture of refractory alumina cement including barium or strontium and alumina as the main chemical components. Specifically, the mixtures of raw materials for the manufacture of cement are obtained by appropriately performing a thermal treatment on mixtures of carbonates and chlorides.
Japanese Unexamined Patent Application, First Publication No. S58-26079 and Japanese Unexamined Patent Application, First Publication No. S56-104783 disclose castable mixtures with good high-temperature strength, for which strontium aluminate is used as a binder.
Itoh, Mizuno, Kono, Suzuki: Journal of the Ceramic Society of Japan, 89, 10, P. 572-577, 1981 discloses a material produced by adding a commercial high-purity reagent to CaO—SrO—Al2O3-based cement and then mixing and firing the mixture, which shows a property of being hardened with an addition of water.
In addition, Japanese Unexamined Patent Application, First Publication No. S56-104783 discloses a binder for monolithic refractories using mixtures of raw materials for the manufacture of cement having CaO—SrO—Al2O3 composition, which shows improved high-temperature slag resistance, compared to binders with CaO—Al2O3 composition.